Determination of influence of polymorphism of gene of erythropoetin receptor (EPOR) on productive qualities of sows and reproductive characters of boars of Belarusian meaty breed was realized in the conditions of the Republic of Belarus. Research results proved the possibility of EPOR gene application as a genetic marker which determined productive abilities of swine of Belarusian selection breed. Frequency of undesirable allel EPOR**c of EPOR gene in the analyzed swine stock balanced within the frames of wide range: from 44% for Belarusian meaty breed sows up to 78% for Belarusian Kripnaya Belaya breed sows. Analysis of influence of genotype with EPOR gene on multiple fetation of sows of Belarusian meaty breed showed that sows with the preferred genotype (EPOR**tt) statistically reliable (P less than 0,01) exceeded sows with undesirable genotype (EPOR**cc) in accordance with number of alive birth piglets on 1,7 heads. Among sows of Belarusian Kripnaya Belaya breed with genotype EPOR**ct there were stated multiple fetation indexes exceeding the sows with genotype EPOR**tt on 0,5 heads. Desirable EPOR**tt genotype irrespective of sow age rendered the positive influence on their multiple fetation. It was recommended to realize genetic testing on determination og polymorphism of gene of erythropoetin receptor among the animals of Belarusian meaty and Belarusian Kripnaya Belaya breeds. Selection of parental pairs of the selection nucleus was recommended to realize taking into consideration genotypes, giving preference to animals with EPOR**t allel

Application in diets of breeding bull calves of an optimum dose of selenium (0,4 mg on 1 kg of a solid of a diet) renders positive influence on formation of reproductive ability of bull-calves: promotes increase daily average gains live weight on 7,1%, indicators of natural resistance – on 0,6-6,7% and to improvement of quality sperm production – on 16,4% during the winter period. During the summer period daily average gains live weight on 6,8%, indicators of natural resistance – on 0,5-13,9% and to improvement of quality sperm production – on 15,7% accordingly

Feeding replacement calves of 369-460,8 kg of live weight with diets of non-degradable protein level that is 10% higher than approved norm increases metabolically energy transformation into weight gain energy from 19,10 to 20,81 MJ or at 9% that promotes increase of average daily weight gains at 5% and decrease of energy spends at 5% counted per 1 unit of energy for weight gain. Ejaculate volume is increased at 14% and sperm concentration – at 12%

In the conditions of the Agricultural Complex Belaya Rus the highest productive values of sows are obtained in period of the fourth-sixths farrowings. The highest level of reproductive traits is shown by sows of Landrace and Belorusian meaty breeds

Research of the selection efficiency of boars of Belarusian meaty and Large White breeds for reproduction and productivity indices was realized in the selection and breeding centre Zadneprovski in the Republic of Belarus. The influence of 25-percentage level of boar selection for sperm production with the dominancy of relative average values of an initial population on statistically significant difference within the limits P less than 0,05-0,001 was proved. Application of an evaluation criterion of animal breeding abilities by the degree of frequency of departures from a population level with a value which reflects the intensity of selection in shares of an average quadratic deviation made it possible to raise the breeding value of boar of both genotypes in accordance with the productive qualities of descendants in comparison with average sizes of populations of two breeds on statistically authentic difference at P less than 0,05-0,001. Decreasing in the studied indicators of efficiency of offsprings concerning initial fatherly forms could be explained by a stronger influence of environment conditions rather than genetic predisposition of genotypes to the given traits

Studying of peculiar features of external conformation of replacement gilts used for the further closing stage of commercial cross breeding as well as for the further productivity of first litter gilts was realized in the conditions of a swine breeding stock-rearing farm of the Republic of Belarus. In the modern zootechnic classification it is reasonable to divide pigs into 3 constitutional types of their external appearance: leptosome, transitional, and oerisome. In the conditions of industrial engineering the replacement pigs and sows of transitive type in comparison with individuals oerisome and leptosome types were characterized by higher productivity: early terms of insemination (on 3,2 and 3,3 days, respectively); livability of stores at weaning stage (on 5,8 and 5%, respectively), higher litter size at weaning stage (on 7,1 and 6,3 kg), higher input share into the basic pig stock (on 4 and 6%), and a yield of a gross of body weight gain of litter at fattening with a view to farrow (on 8 and 10%). Piglets of the transitive type sows were characterized by the steadier parameters of metabolism in comparison with stores of leptosome type sows (there were less frequently encountered the disturbances of infringements of trace mineral and calcium and phosphoric metabolism). On the basis of the realized research there were developed the technical specifications of the Republic of Belarus 600039106.001-2004 Replacement gilts; Manual on appraisal of quality of pigs for repair of herd of a pig-breeding complex; the Technological instruction on herd repair of a pig-breeding complex; production schedules Normalization of reproductive function of replacement pigs in the conditions of a complex

Influence of various levels of the organic form of selenium of Sel-Pleks on the formation of reproductive function of breeding bull-calves is studied in the conditions of the Republic of Belarus. Feeding of organic selenium to bull-calves promoted volume increase of ejaculate on 5,0%, quantities of male germ cells in ejaculate - on 9,1% and concentration of male germ cells in ejaculate - on 7,5% in comparison with animals in which rations sodium selenit was used. Application in winter period of the premix with inclusion of selenium in a dose of 0,4 mg per 1 kg of a dry matter of a ration allows to increase the quantity and quality of sperm of bull-calves: volume ejaculate - on 9,5%, concentration of male germ cells in ejaculate - on 16,4% (Р less than 0,05) and activity of male germ cells - on 8,9% (Р less than 0,001). Increasing of a dose of selenium up to 0,4 mg per 1 kg of a dry matter in rations of bull-calves in summer period allows to increase quantity and quality of sperm. At bull-calves of the third experimental group the ejaculate volume has increased on 4,5%, concentration of male germ cells in ejaculate - on 15,7% (Р0,05) and activity of male germ cells - on 7,3% (Р less than 0,001).

In the conditions of the Republic of Belarus there was determined the influence of different rates of lithium addition into mixed fodders for sows feeding on hematological indexes and their reproductive qualities. In course of the study there was analyzed the dynamics of body weight of sows over the reproductive period; indexes of productivity of sows (number of born piglets; weight of 1 piglet; litter weight; weight of weanling piglets; number of weanling piglets; etc.); hematological indexes of sows; state of humoral factors of immunity of sows. Research results showed that in case of lithium application in diets of sows there was stated an improvement of hematological indexes and immunity functions and resistance. The optimal level of lithium in rations was 15 milligram per 1 kilogram of dry matter of a diet. This dose essentially promoted the increasing of reproductive performance, piglets weight and milking capacity of sows as well as better viability of piglets.

The analysis of data on a complex of reproductive qualities crossing sows has shown, that the combinations used in the classical scheme of variable crossing have appeared are less effective in comparison with the combinations including foreign meat breeds. It is recommended to change the traditional scheme of variable crossing, having excluded from it the Belarus black-motley breed and having entered foreign breeds of L and D and also to use hybrid male pigs (D x P)

Balancing of mixed feeds for replacement gilts considering the metabolically energy level and essential available amino acids amount increases growth speed of animals at 9,6% (P less than 0,05) compared to mixed feeds prepared in correspondence with detailed norms of feeding; it also decreases terms of animals pedigree usage from 277 to 223 days